Hello @Noman_Ali not to worried about that, according to your statement. Sounds like, yet you did not install IDM chrome extension. Just you need to do, Go to
C:\Program Files (x86)\Internet Download Manager then find
IDMGCExt.crx file, now pick this file and drop this file into your chrome extension page.
Allow ADD extension in your chrome.
After added this extension in your chrome, it will look like this.
If you received this message "Internet Download Manager extension for Google Chrome has been installed." This means that, you have done your job!
Hopefully, now internet download manager will work