Why you may need to add your IP to the list of allowed hosts?
Once configuring Database connection, you may see the following error:
SQL error "access denied for user '....." @'........" (using password YES)
You will see username that you're trying to insert while connecting to your database and your local IP (the IP of your computer that you have Store Managerr installed). The error says that user that we have specified cannot connect to our database from our local IP.
If you're absolutely sure that the username and password is correct, it means that your hosting is blocking all external IPs from being connected to your database. To fix it you need to sign in your Hosting Control Panel and add the IP.
How to add IP if I do not have hosting control panel
If you're using shared hosting, most likely you do not have Hosting Control panel where you can handle those things. It means that you should contact your hosting company and ask them to do the job for you.
Just retype the IP that you can see in your error message and ask your hosting to "Add this ip to your access lists to be able to connect to your MySQL database"
How to add IP if I have cPanel
If you hosting company offers you some control panel, most likely you can grant access on your own.
Let us review such tool as cPanel - one of most popular and widely used management applications.
There's no single way to open cPanel but often you can just add "/cpanel" to your website link to get into. So type /cpanel in browser's address bar and press Enter key.
It should bring some dialog like this one:
To get inside you have to type login and password provided by your hosting company. Often it corresponds to your FTP access details provided by your hosting, so you can try to insert your FTP settings here. In case you do not know your access details, contact your developer or hosting company to get access.
After login you will see something like this:
Click on "Remote MySQL" and you will see Access List section. Type IP address of your home/office computer and click "Add Host" button
You will see page indicating successful operation and your IP in the list
After these steps you can try to connect.
Note: Besides cPanel there are several other management applications which may be used by your hosting. Take this short explanation as general "how to" guide, details shown here may differ from yours.