Verify that you have the following (by simply running the command) and if not use yum install;
jq
sox
flac
dos2unix -V
Ensure dos2unix is executable by the asterisk user (chmod 777 /usr/bin/dos2unix)
Connect FreePBX to Google Cloud
su asterisk
gcloud auth login
CLI will provide you a url. Copy that and paste it into your browser. Google will give you a verification code to copy. Paste it into the cli waiting for a verification code.
Open FreePBX web interface
Go to Settings > Voicemail Admin > Settings > Email Config