You can just put the text before the tag, if you want. I think usually you'd put it all in the same div, so extra credit for that I think.
Like this:
library(shiny)
ui <- fluidPage(
tags$h1("Original"),
tags$a(href="https://www.gofundme.com/f/fantasy-football-mental-health-initiative?utm_medium=copy_link&utm_source=customer&utm_campaign=p_lico+share-sheet",
"If you enjoyed this tool, please consider donating to the Fantasy Football Mental Health Initiative!"),
tags$h1("Revised"),
"If you enjoyed this tool, ",
tags$a(href="https://www.gofundme.com/f/fantasy-football-mental-health-initiative?utm_medium=copy_link&utm_source=customer&utm_campaign=p_lico+share-sheet",
"please consider donating to the Fantasy Football Mental Health Initiative!"),
tags$h1("Revised, alternate 1"),
tags$div(
"If you enjoyed this tool, ",
tags$a(href="https://www.gofundme.com/f/fantasy-football-mental-health-initiative?utm_medium=copy_link&utm_source=customer&utm_campaign=p_lico+share-sheet",
"please consider donating to the Fantasy Football Mental Health Initiative!")
),
tags$h1("Revised, alternate 2"),
HTML("<p>If you enjoyed this tool, please consider <a href='https://www.gofundme.com/f/fantasy-football-mental-health-initiative?utm_medium=copy_link&utm_source=customer&utm_campaign=p_lico+share-sheet'>donating to the Fantasy Football Mental Health Initiative</a>!</p>")
)
server <- function(input, output, session) {
}
shinyApp(ui, server)
Edit: added alternate 2 to demonstrate daattali's great tip.