You can find the 3D models of the terminal blocks on 3DContentCentral and directly download them in STEP format (https://www.3dcontentcentral.com/Search.aspx?arg=terminal block 5). Then, import this model in Altium Designer and use the 3D viewer to set reference points in the pin centers. If snap is enabled in 2D view you can use these to directly align the pads without having to manually set properties like grids, coordinates etc.