Kaseya VSA v8 is supported with the AuthAnvil integration. Not sure which integration you are using, or may want to use please check this article.
Kaseya Login Agent
Please see this article for more information. AuthAnvil has the same integration for VSA R7, R8 & R9.
Kaseya v4.3 Paid Addin
For VSA R8/R9 there is a new v4.4 Addin that is available from the Support Team.
Note: If you do not have a current subscription for the Paid Addin we recommend you contact your Account Manager via firstname.lastname@example.org before requesting the Hotfix from support.
Note: If you do not wish to use the Paid Addin with VSA v8 we suggest you uninstall the Addin from Programs and Features. Once uninstalled you will want to clear the DB. Please follow this article to remove the AuthAnvil integration from the ksubscribers DB.
Not sure which integration is best for you? Please check out this article.