Mango 1 liter (Maybe qt can't remember) bottle treats 10 gal. Pitch at 100 I didn't bother holding at any temp. No starter needed.
Here's a post from pork chop about making a goes that has a lot of good info
So with the MAJOR caveat that I have not had this beer, here's what I would do to get a decent gose base that you can adjust with the proper fruit additions to get you close. I'm not going to call it a clone, by any means, but it'll get you a solid gose that you can tweak to get it the way you want.
You'll need to decide if you're going to keep the lacto alive in your beer, or if you're going to kill it off prior to pitching yeast. Killing the lacto eliminates the risk of contaminating your equipment (treat it like any other clean ale), but live lacto will make for a better product in the long run as it will change in the bottle. If you keep the lacto alive, just get a spare plastic carboy that you can use just for sours, an extra auto-siphon, and bottling bucket/spigot/bottling wand. Or just practice really good sanitation and trust that Star-San will kill wild yeast and bacteria (which is what it is supposed to do).
Step 1 - get yourself a quart container of mango Goodbelly probiotic juice. Lots of grocery stores have it, or it'll almost certainly be at a natural food store. This will contain the lactobacillus for souring the wort.
All grain, mash at 148F and sparge to get 5.5 gallons 1.045 wort. Traditional grist is a mix of pils and wheat, I like a 60-40 split, so about 5# pils and 3.5# white wheat malt.
Extract, use 5# DME for 5 gallons wort. I would probably do 3# pilsner or extra light, and 2# wheat DME.
Collect your wort in the kettle, and either do a short boil (5 minutes) or pasteurize at 170F for about 10 minutes. NO HOPS!
Chill wort to 90F. If you have food-grade lactic acid, adjust kettle pH to 4.4-4.7. This is to keep spoilage bacteria at bay while it sours, as added insurance if your sanitation isn't perfect, and to improve the foam on the final product. If you don't have a pH meter, add around 5ml 88% lactic acid, maybe 10ml if your water is pretty hard. If you don't have lactic acid on hand, go for the 5 minute boil instead prior to chilling and don't worry about it.
If you want to kill the lacto, once the wort is at 90F, shake up your carton of Goodbelly and dump about half into the wort in the kettle. Seal it up as best you can, and put it aside for 18-24 hours. Don't worry about purging the headspace with CO2, it won't do any good. Let it cool to room temperature.
If you're going to keep the lacto alive, transfer it to your carboy once it's at 90F and add your Goodbelly. Airlock it and set it aside to cool to room temperature.
After 18 to 24 hours at room temperature, taste the soured wort. There should be no krausen, but the wort should be nice and cloudy. It should be sweet but with some tartness, like a lemonade. If you have a pH meter, take a measurement and see if the pH is 3.2-3.5. It should be.
If you left the wort in the kettle, go ahead and finish your boil, go for the full 60 minutes so you don't have any DMS. Chill to ale pitching temperatures, and pitch 2 packets of US-05. You'll need the extra cell count due to the low pH.
If you are not killing the lacto, just add your 2 packets US-05 to the carboy. Don't worry too much about headspace, as you won't get nearly as thick of a krausen with the low pH, but a blow-off tube is never a bad idea.
Fermentation is usually done within 10-14 days. Bottle or keg, it's nice at higher carb levels like 2.7-3.0 volumes.
For a traditional gose, I like 15g sea salt per 5 gallons. This gives you a subtle hint of salt, and you can always add more later. 15g coriander is traditional at flameout. Skip the coriander if you're going to use the grapefruit and cactus fruit like in this beer.
To get close to this one, I'd start with 15g salt and the zest of 1 grapefruit at flameout. Maybe even the juice, but don't get any of the bitter pith in your beer. For the cactus fruit? No idea - you're on your own for that one!