Use Safari. Do not use Chrome or any other browser.
To install on iPhone you have to register first. This is due to Apple policies. Once done, you can send an email to Michal, who has to re-build the app for you. Once he has done it, you can follow the download link above and agree to installation.
Go to Settings -> Security and turn on Unknown sources. Once done follow the download link above. Chrome will ask you (possibly several times), if you really want to keep the file. Say yes. Then say OPEN, click on the file name (it will be something like dwa-1.0.8-2016-07-01-1234.apk) and agree to to app installation.