On installing Shipturtle, only you (the merchant) have access as an Admin. You can view all Products, Orders and Settings and configure the apps’ settings as per your requirements and workflow. Give Vendors access to it once you are ready by creating Users for them.
Read https://www.shipturtle.com/knowledge-base/adding-users-and-logging-into-shipturtle/ to understand how to create Users.
Vendors can login by going to app.shipturtle.com. (This link is replaced by a custom URL in case the merchant has taken a Whitelabeled plan)

Admin (Merchant) view of App with all access

Vendor View of App with limited access to only their Orders and Products

Adding a new Vendor from Vendor Registration Page

We have a facility for you to add a Vendor Registration page on your Website – https://www.shipturtle.com/knowledge-base/add-vendor-registration-page/.
Once approved, create Users for the new Vendor as above to give them access.