Remember that Lertap5 runs with Microsoft Excel. Your computer must have a copy of Excel in order to be able to run Lertap5. Excel is part of the suite of programs which Microsoft refers to as "Office". Other apps in the Office suite include Word, Access, and PowerPoint.
The Lertap511.zip file with the latest version of Lertap5 may be downloaded using this link -- this version works on both Windows and Macintosh computers. It may also be downloaded from this OSF Link.
The ReadMe-First.pdf document is a must read after Lertap511.zip has been downloaded (or even before, for that matter).
As mentioned in the ReadMe-First document, once the Lertap511.zip file has been downloaded, it must be unzipped, resulting in a folder with the three Lertap5 Excel files and supporting pdf files.
Users should make sure that their computer is running the latest version of Excel -- this may be especially important on a Mac as Excel for the Mac seems to be playing a bit of "catch up" with the Windows versions (the development of the Mac version has historically lagged a bit).
A document covering the on-going development of Lertap5, with version numbering, is available here.