There are two ways to do it.

1. Through partner access. But since you’re on this page, that option probably didn’t work for you :)
2. The second way is by adding a team member directly to the page.

Let’s go with the second one:

Go to the Pages section on Facebook and click on the page you need

Click the Switch Now button

In the left menu, select Settings, then Page Settings, and go to Page Access

At the top section called People with Facebook Access, click Add New

Enter the link to the page provided by the project manager and select the user.

Click Give Access

All done. You’re awesome!