It looks like you have reached out to our Support Team regarding this issue before, and they replied with a suggestion of:
It seems like to be able to use Lark with Zapier you need an app from their directory!
This is what I was able to find:
Due to the the way the Lark app integrates with Zapier, user is required to install a mini program from Lark's own App Directory first before he/she can proceed to Zapier to start the integration. This is where the mini program (called Zapier Connector) is listed:
Permission authorization happens here when user tries to install the connector at the beginning; Once user agrees here, he/she is deemed to have granted permission to authorize Zapier to access Lark so later on when user actually starts the integration on Zapier platform and tries to log in Lark account, he/she doesn't have to review these permissions again.
Can you please confirm if you have already installed this app before connecting the Lark account to Zapier however are still facing an issue with the Select Guests field?
Could you please confirm if you have followed the suggestion of our Support Team?