Now that I’ve upgraded, how do I share the storage with my family?

Read and perform ALL the steps provided in this support article:--> Share iCloud+ with your family - Apple Support.

If the issue persists, please contact Apple Support directy, using this link:--> Get Support

Regards

Giulio

On your iPhone, iPad, or iPod touch

Go to Settings > [your name]. Tap Family Sharing. Tap iCloud Storage. Follow the steps to share your existing plan.

Share iCloud+ with your family - Apple Support (IN)