Tiledesk uses Chat21 as messaging platform. Refer to Architecture overview to undestand the product's modules. In detail the tiledesk-server component uses Chat21 channel for sending chat messages, creating groups, etc.
So in order to correctly configure your Tiledesk installation you MUST configure the following properties:
FIREBASE_PRIVATE_KEY. You can get it here. It is in the form: -----BEGIN PRIVATE KEY-----\ABCD78261TGV...HGAGBA82727\n-----END PRIVATE KEY-----\n. More info about firebase private key here.
FIREBASE_CLIENT_EMAIL. You can get it here. It is in the form: firebase-adminsdk-******@************.iam.gserviceaccount.com