Even after Dynamsoft Service has installed properly and works on earlier versions of Chrome, it doesn't work anymore on Chrome 58+ and keeps prompting you to download and install the Service again on a secure page (SSL).
A permanent solution will be included in v5.2.1 and it is coming soon.
If you don't wish to upgrade, then below are the temporary solutions:
As the issue is caused by the certificate update introduced in Chrome 58, you can use a HTTP site.
1. Open 'https://127.0.0.1:18626/' (for version 5.1 or 5.0, open 'https://127.0.0.1:18621/') in Chrome and you'll see the following
2. Click 'Proceed to 127.0.0.1 (unsafe)'. Then you might see either one of the followings.
Remains on the same page (before v5.2)
"Configuration Information of Dynamsoft Service" (v5.2)
3. Go back to your page and it should start working again.