Can not customize theme

Hello,

I have been having a few issues with wordpress lately. Part of my issues are that I cannot update plugins without the website going into maintenance mode and the updates being unsuccessful. Also having troubles uploading media. I am trying to narrow down the cause.

I am unable to open up the customization option for the construction field theme. I get rerouted to a temporarily unavailable page. Does anyone know if the problem lies within the theme or is it caused be another issue altogether?

Any help would be greatly appreciated.

Thank you