I am not a FlexTool expert.
However, there might be a clue in your error message...
Is your normal Windows user-name 'Administrator' ?
Usually you'd choose something like 'Wenzhi' ?
Assuming it is your normal Windows user-name...
When you initially installed SketchUp did you do it in the proper way ?
Even if you [as a normal Windows user] have admin-powers you must install complex apps this way...
[Note that if SketchUp is already installed you should close it, then choose the Repair option offered...]
Find the SketchUp installer exe file - probably in your downloads folder ?
Select that exe file's icon.
Right-click > context-menu > "Run as administrator"
When prompted choose "Repair" and agree to all prompts thereafter...
[If it's a fresh install choose "Install" !]
Installing it in any other way - even if you have full admin-powers is not the same thing.
Double-clicking on the exe file's icon might 'Run' it, but NOT as 'the administrator'.
It's not recommended to run SketchUp while logged in as the full 'system-administrator' - but if you have another user-name called [confusingly] 'Administrator', probably with admin-powers that IS OK, BUT you will still need to use "Run as administrator"... as explained...
If you have really messed up permissions on the C:/Users/Administrator/AppData/Roaming/SketchUp path then you might also need to fix then using Right-click > context-menu > Properties > Security > Edit and ensure that every entry has 'Full Control' set and that this permissions trickles down to apply to all subfolders and files in the tree...