As described on official documents (driver’s license, passport etc.)
Enter address in-line with commas separating lines of the address. This MUST include house/apt name/number, street, town/city, postal code and country
User settings -> advanced -> developer mode on then user settings -> My Account -> 3 dots next to your name
You can find that by following these instructions. https://help.steampowered.com/en/faqs/view/2816-BE67-5B69-0FEC We need your 64-bit Steam ID (i.e. 76561198#########)
Tell us about your history with games like ’83 and any previous experience of alpha/beta testing.
Terms & Conditions

Tester Terms & Conditions

Blue Dot Games Ltd will use all data submitted in the playtester application form above for, AND ONLY FOR, the processing of applications to be a playtester of the game 83 and for the processing of test data that feeds into the development process of that game.
Such data will not be passed on to any third parties and will be stored for a maximum of 3 months after the game is released.
Requests for personal data to be removed from our database can be submitted at any time to info@bluedotgames.com