Fortigate vpn bgp with google cloud

Hi

i can't finish the bgp to gcp configuration, basically i have the vpn up, one tunnel all ok it works but if i do cloud router and bgp i can't get it up. if i configure bgp ip and peer ip they are all ok asn as well, but they don't show up, i have the wan1 with gcp tunnel which is called gcplab, but the 169.x.x.2 ip of the /30 i have to configure it somewhere?
in gcp i have the other ip 169.x.x.x.1
do i have to put firewall rules on fortigate side? because i can't find any documentation on how to proceed?
thank you all for the help