Free VPN-s are shit and their IPs are most likely spammed to death. For Facebook they are useless and even paid VPN-s and datacenter proxies are useless. Residential IPs and 4G are the best ways to go.
Do you mean that the VPN disconnects in the process of the account creation? In that scenario, the data you send is not tunneled through the VPN anymore and your real ip can get get revealed without you hitting any button.
Keep the VPN connection alive, while creating the accounts. Disconnecting/reconnecting in the process of the account creation is not good, because you never know, when your real ip might leak between disconnecting from and reconnecting to the VPN.