All you have to do is under the ImStore menu is create a gallery “add new”
is going to show you all the options for the gallery.

To upload images look for the box title “Import Images”. There are 3 options to upload images, the first will allow you to select images from your computer.

The images as they upload will display just below. Once you have your images loaded add a title to your gallery and click on publish — blue button on the right-hand side — once publish you can click on the view gallery.

you need to set your album theme under settings > general > album theme. Try using the page or also you can move the “taxonomy-ims_album.php” and make modification as needed the file is located inside the plugin folder in the theme folder