WC Vendors installed/ - but impossible to get it working

Hi Support-Team,

we setup a new wordpress multisite installation - dealsmart.biz - activated just with minimum of plugins --> buddypress, woocommerce and wc vendors. Those plugin are necessary in order to get both paid theme BuddyBoss incl. WC Vendors PRO up and running.

The issue: something does not work out with wc vendors installation but what might it be?

What we did:
installed fresh wordpress 4.6 only (so 4.6.1 not updated) to ensure wc vendors is a tested version.
activated just the minimum of needed plugins theme + buddypress + akismet + wpmudev dashboard to ensure, none of the active plugins might interfere.
installed everything according installation guide
contacted hosting provider for help but they believe it might be multisite ... unfortunately provider does not support multisite.

Therefore we are asking you guys for help which is most appreciated. Support access is granted.
Thank you.