Fotomoto only works with TTG Highslide Gallery Pro 2.0 and higher.
For the latest TTG updates and support, go to TTG's website
In your Fotomoto account navigate to Site (1) > Settings (2) and click the Change (3) link.

From the Extra Script/Template drop down menu, select TTG Gighslide Gallery Pro from the list, and then click the Save button.

Make sure you have your Fotomoto site key, which can be found under Site>Settings in your Fotomoto account.

Select Appearance from the control pane, then select Fotomoto from the E-Commerce Mode drop-list.

Now just paste your site key into the Fotomoto options field.

Fotomoto should now work with TTG Highslide Gallery Pro.