The plugin has been developed to be "theme agnostic" and it doesn't require any fancy theme feature. The only requirement, from a theme perspective, is that your theme supports one or more widget areas. This is necessary because the Currency Selector is a standard WordPress widget, and has to be dropped on a widget area.
Please note that, despite the generic nature of the Currency Switcher, we cannot guarantee compatibility with 3rd party themes. Testing is performed exclusively on WordPress and WooCommerce basic themes (e.g. TwentySeventeen, Storefront, etc). Although unlikely, it may be possible that other themes can have compatibility issues.
WPLMS theme might be incompatible with the Currency Switcher. Such theme introduces a large set of features that radically change the way WooCommerce works, and many of those changes could conflict with the Currency Switcher logic.
We will try to help should theme related issues arise, but we would like to remind you that 3rd party software (including themes) is not covered by free support. Therefore, we won't be able to provide free support with troubleshooting of themes' look and feel and features.