'nvm' is not recognized && npm install

Question

I got home exam and I have 2 problems. (Windows)

1. When I run nvm use 12.7 in Powershell, I get this message:

nvm : The term 'nvm' is not recognized as the name of a cmdlet, function, script file, or
operable program. Check the spelling of the name, or if a path was included, verify that the
path is correct and try again.
At line:1 char:1
+ nvm use 12.7
+ ~~~
    + CategoryInfo          : ObjectNotFound: (nvm:String) [], CommandNotFoundException
    + FullyQualifiedErrorId : CommandNotFoundException

2. When I run npm install:

lerna ERR! npm install exited 1 in '@ans-exam/client' 
npm ERR! [email protected] bootstrap: `lerna bootstrap`

I have installed nvm, npm and node.