There’s no setting - just have patience. The time taken for Roon to add an album seems to vary, possibly driven by the amount of crosslinking that has to be done in the database for each album, and some have more links than others.
I think you’ll find that multiple clicking on the + sign has no effect on speeding things up - the operation is begun with the first click.
For reference, how many tracks do you have in your library?
FWIW, I have 38k+ tracks and adding an album from Qobuz is near instantaneous. Broadband 75M download 20 up via a bog standard BT router.
I have had 2 different mesh wifi systems and both caused me endless expense & problems which disappeared when i went for a “standard” router…
Thanks. I’m going to stick with my mesh router because I like having broadband throughout my entire house and I didn’t have that with a solitary router.