can't verify gpg key on linux mint

the instructions say to do this :

For Debian, Ubuntu, or Mint:
1. Open the Terminal.
2. Import the GPG public key using the command:
```
gpg --import ~/Downloads/package-signing-key.pub
```
3. Verify the signed file with:
```
sudo apt install dpkg-sig && dpkg-sig --verify ~/Downloads/zoom_amd64.deb
```
4. Enter your user password when prompted. A successful verification will show "GOODSIG _gpgbuilder".

the problem is when i type the 3rd command which starts with sudo apt install

i get the error

E: Unable to locate package dpkg-sig 

i can’t figure out how to actually check the zoom file

i have two files downloaded into my download directory, they are:

zoom-amd64.deb

and

package-signing-key-6-7-5.pub

so i’m not sure what i’m doing wrong. can someone help figure out what command(s) I need to be running to check the gpg key?

i am on linux mint 22.3 Zena