[2022] How to Invite/Be Invited *without* Xbox App?

Hi there. You can see if this article offers anything helpful for your situation, but if not, you can use the link at the bottom of the article to raise a support request directly with our dedicated support team: https://support.seaofthieves.com/hc/articles/360014229460-Steam-Invites-Sending-receiving-Invites-between-Steam-users