No sidebar and no way to create an album

Are you in Full Screen mode? Then no Menu Bar may be available until you move the cursor to the very top of the screen-- then the menu bar should slide down into view. And under "View" is the choice to "Always Show Toolbar and Sidebar in Full Screen."

Personally, I don't care for Full Screen. Also in "View" is "Exit Full Screen." Then you can drag the corners of the window to the size you like, including filling the screen without being "Full Screen."

The sidebar may vanish in Full Screen mode, as Richard explained.

There is another possible reason for the sidebar missing - the sidebar will also vanish, if the Photos window is very small. This can happen, if you are using a scaled resolution for the Display. If the sidebar does not reappear, after you drag the corners of the Photos window to enlarge it, open the System Settings for the Display and set the resolution to "More space", so you can make the Photos window larger.