I am trying to connect adb device and it showing \"Please check the confirmation dialog on your device\" ..but there is no adb confirmation(rssi) dialog.
I had the same problem. I have two different Linuxsystems on my computer. The installation on MX-Linux 19.3 xfce was very easy and working after a short time. The installation on Mint 19.3 Cinnamon would not work. All instructions i found in google didn't solve my problem. After deleting the files adbkey and adbkey.pub in my directory, i didn´t get these files, when i followed the instructions. I got always the status "device unauthorized" and did not get the "confirmation dialog on my device". Then i had a divine inspiration. In a console i gave me root permission via su and started there droidcam. I imediately got the confirmation dialog on my smartphone and the driodcam was working fine. The files adbkey and adbkey.pub are now in the directory /root/.android.