Currently on your Site, you have made the Footer with Widgets. So, under the available Footer Column Layouts, there isn’t such a Layout available right now which adds the horizontal column after the 4 vertical columns due to this you can’t add a HTML Block in an horizontal way like you want.
So, there are two ways right now. Either you create your whole Footer with HTML Block in this way you can add Content of your choice at your place in the Footer. So, you can also add the Disclaimer content easily in that.
Or if you want to go with the Widgets one then you can add Disclaimer text content next to Copyrights text: https://snipboard.io/zVHRUr.jpg
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