Hello,
What was the previous firmware version you had installed? The shortage of space and erased configuration might be a result of improper migration between firmware versions, if the difference was higher that two or three iterations.
Could you login to the router via CLI/SSH and provide the output of the following command:
Also, do you have Storage expansion option enabled in Services -> USB tools -> Storage memory expansion page? As it is necessary, in order to use the extra memory to install additional software packages.
For further instructions, please refer here.
Best regards,