Hi Megsfer256,
As you posted from the appropriate article on this topic, there are 2 things you may need to check which could affect device changes:
1) Check for Screen Time restrictions by following the information from Use Screen Time on your iPhone, iPad, or iPod touch. If you have any current restrictions in place, you may disable those temporarily to see if the desired Home Screen changes will then work.
2) If your iPhone is managed by a company or school, some changes may not be allowed or be restricted. The support article Install or remove configuration profiles on iPhone shows where to look to see if such profiles have been installed. If so, check with the company that provided the profile before removal to prevent unintended side effects.
Barring those, restarting your iPhone and ensuring you have the latest version of iOS installed are steps that should also be taken.
Regards.