It's important to link your accounts to Meta Business Suite so you can assign access to the accounts without sharing passwords, and better govern your organizations data privacy.
To get started, you'll need a Meta Business Suite account. If you don't already have one, create one using this official guide.
Next, you'll need to add your Facebook pages and add your Instagram accounts.
Now that that's finished you will be able to assign your team members access to the Facebook Pages and Instagram Accounts with proper permissions as desired.
When they leave your organization be sure to terminate their access to ensure your data privacy and account integrity.