Sonic Mania EU Steam Altergift

In order to receive and activate the game:

You will receive a gift link to a website. Open that link in your web browser.
Depending on the prompt please provide your Steam profile link or login via Steam 
If needed choose the same country as your store country found in Steam account details. You can check this setting here.
Automated bot system will add your Steam account to friendlist.
After you accept the friend request from bot, it will send you your purchased game as a gift.