W: There is no public key available for the following key IDs:
9D6D8F6BC857C906
W: There is no public key available for the following key IDs:
7638D0442B90D010

Fix:

apt-key adv –keyserver keyserver.ubuntu.com –recv-keys 9D6D8F6BC857C906
apt-key adv –keyserver keyserver.ubuntu.com –recv-keys 7638D0442B90D010