Generate unique_id from signup process and update that in another table based on certain condition

hi there…new to bubble and also to building a software…so pls pardon my ignorance…

I have two datatypes…
a. Users (default) - where I have added a custom field Tenant-ID and the default field Email.
b. AccountUser - where I have Tenant-ID, User-ID, Email and few other fields
c. Tenant - where I have some basic tenant related data fields. The Unique-Id from this datatype is what I use as tenant-ID in the Users and AccountUser datatypes

When the user first sign-up, I trigger a signup workflow, where I set the name, email, Tenant-ID etc to user datatype. For the Tenant-ID, I do a search in my AccountUser datatype where email = signup input email. (see below). I also want to update the AccountUser datatype for that specific user’s User-ID field, with the Unique-Id generated from Signup flow (User). Could you pls guide me through this? I have been sitting on this for so may hours…thanks for your help