Installed fine on my Huawei running Android v7.0. I entered the date of my latest graft and it calculated and showed day 10, 30 and 35 etc. I normally use one of the spreadsheet versions on my PC so I'm not sure whether I will prefer to use the phone instead, but it certainly works fine, so congratulations and thanks for your efforts.
It seems a bit bare bones for an app, are there any other calculations that could be included? Perhaps syrup weights which you non-metric folks seem to struggle with (!).