Welcome! This forum has a treasure trove of great info – Scouters helping Scouters! Just a heads up, though - all content, information, and opinions shared on this forum are those of the author, not the BSA.
IA/SB+ won’t let me log in due to thinking I’m offline. The username and password text boxes are disabled and the sign in button is replaced by a crossed-out wifi symbol. It’s got a separate sign-in process from the rest of scouting.org, and I had not problem logging into my.scouting.org then accessing legacy SB and these forums.
I just logged in to Scoutbook Plus without issue using my Apple ID. What type of ID do you have setup for Scoutbook? Are you using advancements.scouting.org?