Hope you are doing well and sorry for the trouble. AS described you are unable to download the Adobe Acrobat Reader DC to Macbook Air
Would you mind sharing the workflow/steps you are doing to download the application? What is the link you are using to download?
Also please share the version of the Mac OS you are using?
Please try to download the Acrobat Reader DC using the link https://get2.adobe.com/reader/ and see if that works for you.
Let us know if you experience any trouble and need more help.
Acrobat Reader does not let you use a scanner (or stop you). Please show the info which seems to say that, so we can help. Also, what version of macOS do you have? Let us know if you need help finding out.
You must wait until the download is finished.