You get a code and a QR for the others to scan. Hosting needs the venue code from your table sign at the Haven — once your phone has it, it keeps it.
Anyone, anywhere — no venue code. Just the 5-letter code from whoever is hosting.
Hosting a table is a Northwood Game Haven thing — the code is on your table sign, the table tents and the TVs, in Chippewa Falls, Wisconsin. Scan the QR on the sign and this fills itself in; ask any Guru if you cannot find it.
Joining a table doesn't need this. If someone at your table is already hosting, go back and enter their 5-letter table code instead — that works anywhere. So do the Life Counter, First Player and the RPG tools, offline, with no code at all.