Meticulously cleaned D7 database successfully imported to EMPTY DB of fresh Backdrop codebase.
On install, entering db info screen results in "Table variable already exists".
I can push past this screen by entering install.php again, results in:
./sites/PATH_TO_FILES/files/config_LONG_NUMBER_/active directory must be completely empty to proceed with installation. Empty this directory or specify a different directory in settings.php.
Whatever tried, can't get beyond this screen repeatedly. Nothing helpful in logs. I've redone DB, user, + host, watched + tested both locations of settings.php + files (root + multisite), filled out settings.php manually. No luck searching.
Permissions seem good...
settings.php 644 owner
files 755 owner
on either location of these.