How to include tooltip/popper in FullCalendar 5?

Question

I am trying to incorporate tooltip/popper into my Fullcalendar so that when I hover over an event it shows the full title (it is truncated in the calendar). I have tried eventDidMount and nothing happens when I place my cursor over the event (and no console errors). I have also tried eventRender (Tooltip in FullCalendar) and there is an error in the console log "main.min.js:6 Unknown option 'eventRender'".

I am using Bootstrap 5 (I do not know if that is relevant).

I am including:

<!-- Tooltip -->
<script src='https://unpkg.com/popper.js/dist/umd/popper.min.js'></script>
<script src='https://unpkg.com/tooltip.js/dist/umd/tooltip.min.js'></script>

I have copied the css from the example: Event tooltip with eventDidMount and Tooltip.js

/*Tooltip and popper */
.popper,
.tooltip {
  position: absolute;
  z-index: 9999;
  background: #FFC107;
  color: black;
  width: 150px;
  border-radius: 3px;
  box-shadow: 0 0 2px rgba(0,0,0,0.5);
  padding: 10px;
  text-align: center;
}
.style5 .tooltip {
  background: #1E252B;
  color: #FFFFFF;
  max-width: 200px;
  width: auto;
  font-size: .8rem;
  padding: .5em 1em;
}
.popper .popper__arrow,
.tooltip .tooltip-arrow {
  width: 0;
  height: 0;
  border-style: solid;
  position: absolute;
  margin: 5px;
}

.tooltip .tooltip-arrow,
.popper .popper__arrow {
  border-color: #FFC107;
}
.style5 .tooltip .tooltip-arrow {
  border-color: #1E252B;
}
.popper[x-placement^="top"],
.tooltip[x-placement^="top"] {
  margin-bottom: 5px;
}
.popper[x-placement^="top"] .popper__arrow,
.tooltip[x-placement^="top"] .tooltip-arrow {
  border-width: 5px 5px 0 5px;
  border-left-color: transparent;
  border-right-color: transparent;
  border-bottom-color: transparent;
  bottom: -5px;
  left: calc(50% - 5px);
  margin-top: 0;
  margin-bottom: 0;
}
.popper[x-placement^="bottom"],
.tooltip[x-placement^="bottom"] {
  margin-top: 5px;
}
.tooltip[x-placement^="bottom"] .tooltip-arrow,
.popper[x-placement^="bottom"] .popper__arrow {
  border-width: 0 5px 5px 5px;
  border-left-color: transparent;
  border-right-color: transparent;
  border-top-color: transparent;
  top: -5px;
  left: calc(50% - 5px);
  margin-top: 0;
  margin-bottom: 0;
}
.tooltip[x-placement^="right"],
.popper[x-placement^="right"] {
  margin-left: 5px;
}
.popper[x-placement^="right"] .popper__arrow,
.tooltip[x-placement^="right"] .tooltip-arrow {
  border-width: 5px 5px 5px 0;
  border-left-color: transparent;
  border-top-color: transparent;
  border-bottom-color: transparent;
  left: -5px;
  top: calc(50% - 5px);
  margin-left: 0;
  margin-right: 0;
}
.popper[x-placement^="left"],
.tooltip[x-placement^="left"] {
  margin-right: 5px;
}
.popper[x-placement^="left"] .popper__arrow,
.tooltip[x-placement^="left"] .tooltip-arrow {
  border-width: 5px 0 5px 5px;
  border-top-color: transparent;
  border-right-color: transparent;
  border-bottom-color: transparent;
  right: -5px;
  top: calc(50% - 5px);
  margin-left: 0;
  margin-right: 0;
}

My js:

eventDidMount: function(info) {
    var tooltip = new Tooltip(info.el, {
        title: info.event.title,
        //title: event.title, //tried this
        //title: title, //tried this
        //title: fc-event-title, //tried this
        placement: 'top',
        trigger: 'hover',
        container: 'body'
    });
},